The invention relates to a semiconductor device and method for its production. For this purpose, the semiconductor device includes a first electrode and a second electrode located on surfaces of a semiconductor body and an insulated gate electrode. The semiconductor body has a contact groove for the first electrode in an intermediate oxide layer. Highly doped zones of a first conduction type are arranged in edge regions of the contact groove.
Highly doped zones of a complementary conduction type in the source connection zone act together with a highly doped emitter of a first conduction type of a monolithically integrated free wheeling diode. The concentration of doping material of these highly doped zones is higher by a power of ten than that in a body zone. These highly doped zones are located in the upper region of the body zone of a bipolar IGBT (insulated gate bipolar transistor) or a unipolar MOSFET. In the reverse mode of the semiconductor device, these highly doped zones determine the effect of the anode emitter of the free wheeling diode and result in a low forward voltage VF combined with a high stored charge in the semiconductor device.
In hard-switching applications, such a semiconductor device with a monolithically integrated free wheeling diode is less useful than a single diode solution with a switched-in free wheeling diode, because the reverse current peak, the diode switch-off energy and, in IGBT components, the IGBT switch-on energy are too high in a monolithically integrated free wheeling diode. As a result, the emitter efficiency of the complementary conduction type of the monolithically integrated free wheeling diode is too high, resulting in the flooding of the charge carrier in the drift zone, thus reducing the switching capacity of the component.
To reduce this flooding of the charge carrier, the life time of the charge carrier can be reduced locally or homogeneously, for example by irradiating a semiconductor wafer after its production with electrons or protons or by reducing the life time of the charge carrier in the semiconductor device by using rapid gold or platinum diffusion. This reduction of the life time of the charge carrier, however, has the disadvantage that not only the forward voltage VF but also the saturation forward voltage VCEsat between the first and second electrodes rises. With the rise of the forward or saturation voltage, power loss also increases owing to the heating of the semiconductor device in the forward mode, reducing the efficiency of the semiconductor device as a whole. The region bounded by the outer edges of the highly doped zones of a first conduction type is also referred to as source connection zone, because it includes a highly doped zone and a contact zone of the first (source) electrode with the body zone.
For these and other reasons, there is a need for the present invention.